These days, it known practice to mount, in each wheel of a motor vehicle, for example on the valve or on the internal face of the tire, a unit for measuring one or more parameters concerning the inflation gases of said tire such as, for example, the temperature and/or the pressure thereof.
As is known, a measurement unit of an existing solution comprises a temperature measurement sensor, a pressure measurement sensor, a microcontroller, a battery supplying electrical energy, an accelerometer and means for communicating wirelessly with an electronic control unit of the vehicle.
In order to save the supply battery, the measurement unit operates in two different modes: a standby mode and an active mode. In the standby mode, corresponding to the stopping of the vehicle, the microcontroller measures, via the different sensors, the parameters of temperature and of pressure of the inflation gases of the tires and of acceleration of the wheels at a low, so-called “standby” frequency, for example every minute, and analyzes them without sending them to the electronic control unit in order to save the electrical energy supplying the measurement unit. The measurement unit remains in standby mode as long as the vehicle is stopped, that is to say as long as the measured acceleration of the wheels is zero. On the other hand, when the vehicle starts moving and the acceleration becomes non-zero, the measurement unit switches to active mode. In this active mode, the microcontroller measures the parameters of temperature and of pressure of the inflation gases of the tires and of acceleration of the wheels at a high frequency, for example every 16 seconds, and sends them, via the wireless communication means, to the electronic control unit at a report frequency, for example every minute. The electronic control unit analyzes these measurements, notably the pressure of the inflation gases of the tires, in order to detect a tire inflation fault when using the vehicle and inform the driver thereof.
The use of an accelerometer dedicated to detecting the movement of wheels does however significantly increase the complexity and the cost of the measurement unit.